Ocean Currents

Warm currents flow away from the equator.

Cold currents flow toward the equator.

Ocean Currents

SunWindCoriolisGravity

Factors Influencing Currents

Energy from the Sun heats the water. Warm water is less dense that cold water.

Warm water rises, and cold water sinks.

As warm water rises, cold water moves it to replace it.

Sun

Convection Cycle

Just as wind moves from high pressure to low pressure areas, so does the water.

Winds blow across the surface of the water, causing friction.

The water piles up because the surface currents flow slower than the winds.

Wind

Wind

As water piles up and flows from high pressure to low pressure, gravity will pull down on the water.

This forms vertical columns or mounds of water.

The Coriolis Effect causes the water to curve.

Gravity

Causes water to move to the right in the Northern Hemisphere

Causes water to move to the left in the Southern Hemisphere

The Coriolis Effect

The Coriolis Effect

Make up 10% of oceans’ water Up to maximum depth of 400 m Surface ocean currents are caused by the surface wind patterns.

Surface Currents

Surface Currents

Vertical columns or mounds of water at the surface and flow around them

Produce enormous circular currents Five major locations:

North Pacific - clockwise South Pacific - counterclockwise Indian Ocean - counterclockwise South Atlantic - counterclockwise North Atlantic - clockwise

Gyres

Oceanic Gyres

A strong surface current Begins at the tip of Florida Flows up the eastern coastline of the

U.S. Crosses the Atlantic Ocean Causes warmer climate in NW Europe

Gulf Stream

Surface waters blow to the right of the wind.

As less dense, surface water moves off shore, cold, deep, denser waters come to the surface to replace them.

Upwelling

Upwelling

The Great Ocean Conveyor:Helps maintain Earth’s Balance

Make up about 90% of oceans’ water Differences in density cause them to move. Differences in density are related to

temperature and salinity. At high latitudes, they sink deep into the

ocean basins. Temperatures are so cold, they cause the

density to increase.

Deep Water Currents

How are ocean currents produced?

Reflective Question

Abnormally high surface ocean temperatures off the coast of South America

Causes unusual weather patterns across

the globe

El Nino

Starts because the easterly trade winds weaken and allow the warm waters in the Western Pacific to move east toward South America

This changes where the convection current occurs.

Causing rain where it usually doesn't occur and drought where it usually rains

El Nino

El Nino Winter

El Nino Summer

Abnormally low surface ocean temperatures off the coast of South America

Causes unusual weather patterns across

the globe

La Nina

Ocean currents move more slowly than winds. Oceans hold more heat than the atmosphere and

land. Cold currents will cause nearby coastlines to be

cooler. Warm currents will cause nearby coastlines to be

warmer.

Where do the cold currents come from? The warm currents?

Ocean’s Effect on Climate

Predictable Patterns How do these currents affect the climate

of the coastline?

How do our oceans impact climate?

Reflection Questions